diff --git a/docs/TODO_game.md b/docs/TODO_game.md
index 6263126981..a9d8098cb1 100644
--- a/docs/TODO_game.md
+++ b/docs/TODO_game.md
@@ -16,6 +16,7 @@
 	- zoom in too much, what might you see? ;)
 	- loading screen: snakey cars
 	- game intro/backstory: history of seattle urban planning
+	- player context: a drone. people will look up eventually.
 
 ## Tutorial
 
diff --git a/docs/TODO_refactoring.md b/docs/TODO_refactoring.md
index 343dd98fbd..42cfbc00e7 100644
--- a/docs/TODO_refactoring.md
+++ b/docs/TODO_refactoring.md
@@ -21,6 +21,7 @@
 - rename Car->Vehicle?
 - spawning is convoluted
 	- popdat trip -> Scenario SpawnTrip -> pick ped speed and make spawner's TripSpec -> create trip and schedule a Command -> last minute rewriting when executing the command
+- more precise car FSM by putting scheduler pointer into carstate
 
 ## ezgui layer
 
diff --git a/game/src/render/building.rs b/game/src/render/building.rs
index 66dcb9fa23..95625a3dd3 100644
--- a/game/src/render/building.rs
+++ b/game/src/render/building.rs
@@ -81,6 +81,11 @@ impl DrawBuilding {
             );
         }
 
+        // TODO Slow and looks silly, but it's a nice experiment.
+        /*for poly in bldg.polygon.shrink(-3.0) {
+            batch.push(cs.get_def("building roof", Color::rgb(150, 75, 0)), poly);
+        }*/
+
         DrawBuilding {
             id: bldg.id,
             label,
diff --git a/geom/Cargo.toml b/geom/Cargo.toml
index 75bfe2c07a..d7767b3ccb 100644
--- a/geom/Cargo.toml
+++ b/geom/Cargo.toml
@@ -9,6 +9,7 @@ aabb-quadtree = "0.1.0"
 abstutil = { path = "../abstutil" }
 geo = "0.12.0"
 geo-booleanop = "0.2.0"
+geo-offset = "0.1.0"
 histogram = "0.6.9"
 ordered-float = "1.0.1"
 polylabel = "1.3.0"
diff --git a/geom/src/polygon.rs b/geom/src/polygon.rs
index 0247d59a75..b1bacea91d 100644
--- a/geom/src/polygon.rs
+++ b/geom/src/polygon.rs
@@ -1,5 +1,6 @@
 use crate::{Bounds, Distance, HashablePt2D, Pt2D};
 use geo_booleanop::boolean::BooleanOp;
+use geo_offset::Offset;
 use serde_derive::{Deserialize, Serialize};
 use std::fmt;
 
@@ -184,27 +185,17 @@ impl Polygon {
     }
 
     pub fn intersection(&self, other: &Polygon) -> Vec<Polygon> {
-        let multi = to_geo(self.points()).intersection(&to_geo(other.points()));
-        multi
-            .into_iter()
-            .map(|poly| {
-                Polygon::new(
-                    &poly
-                        .into_inner()
-                        .0
-                        .into_points()
-                        .into_iter()
-                        .map(|pt| Pt2D::new(pt.x(), pt.y()))
-                        .collect(),
-                )
-            })
-            .collect()
+        from_multi(to_geo(self.points()).intersection(&to_geo(other.points())))
     }
 
     pub fn polylabel(&self) -> Pt2D {
         let pt = polylabel::polylabel(&to_geo(&self.points()), &1.0);
         Pt2D::new(pt.x(), pt.y())
     }
+
+    pub fn shrink(&self, distance: f64) -> Vec<Polygon> {
+        from_multi(to_geo(self.points()).offset(distance).unwrap())
+    }
 }
 
 impl fmt::Display for Polygon {
@@ -297,3 +288,20 @@ fn to_geo(pts: &Vec<Pt2D>) -> geo::Polygon<f64> {
         Vec::new(),
     )
 }
+
+fn from_multi(multi: geo::MultiPolygon<f64>) -> Vec<Polygon> {
+    multi
+        .into_iter()
+        .map(|poly| {
+            Polygon::new(
+                &poly
+                    .into_inner()
+                    .0
+                    .into_points()
+                    .into_iter()
+                    .map(|pt| Pt2D::new(pt.x(), pt.y()))
+                    .collect(),
+            )
+        })
+        .collect()
+}